AMBE-1000 Digital Voice Systems, Inc., AMBE-1000 Datasheet - Page 32

• Manufacturer Part Number: AMBE-1000
• Manufacturer: Digital Voice Systems, Inc.

4.
4.1
4.1.1
Header
16 bits
(5) 16 bits words of overhead (80 bits)
The AMBE-1000 is not recommended for new designs.
8 bits
ID
Please refer to the AMBE-2000/2020 product line.
Status_0 Status_1 Status_2 Status_3
8 bits
Framed Output Format
Channel Data Format
The channel interface is responsible for outputting the compressed data from the
encoder and inputting compressed data to the decoder.
basic functions the channel interface is also capable of reporting certain events, such as
the detection of a DTMF tone. The channel interface can also control certain selectable
functions of the AMBE-1000™, such as the voice coding rate. This chapter will describe
how the AMBE-1000™ uses the channel interface to multiplex these capabilities.
There are two formats to the data, Framed which is available in both parallel and serial
modes, and Unframed, which is only available in serial mode. Generally speaking the
Unframed mode is used only when the connection between the AMBE-1000™ and the
channel under design is relatively direct, and the designer wants to simplify the
extraction of the relevant voice data.
between the AMBE-1000™ and the channel, the system designer will find that using the
Framed format is more straight forward in implementing the system.
Framed Format
The Framed format is a 17 by sixteen-bit word format.
encoder outputs 17 words, and likewise the decoder expects to receive 17 words. The
format of the input and output frames are detailed below. The first 5 sixteen bit words
are made up of header, ID and status or control information. The remaining 12 sixteen
bit words make up the encoded data bit field. These 12 words, or 192 bits, will be fully
populated with relevant voice data only when the AMBE-1000 is operating in a 9600bps
mode (9600 bits/sec
rate is less than 9600bps, the coded voice bits are filled starting from the MSB of the
first word in the field, leaving any unused bits as zeros. It is important to note here
that even when the AMBE-1000 is operating at less than 9600bps, all 272 bits of the
Framed format (including any unused trailing zeros) must be transferred out of the
encoder and into the decoder.
In Table 4-A, we see the basic Framed data format. As diagramed in Figure 3-A, it is
only the bits in the Voice Data Bits field which are transmitted along with framing
information (data used to locate the start of each frame for proper reconstruction at
the decoder) over the channel. The first 80 bits provide overhead information which is
sometimes useful to the host but is generally not transmitted over the channel.
Table 4-A Basic Framed Output Format
16 bits
The AMBE-1000 is not recommended for new designs.
16 bits
Please refer to the AMBE-2000/2020 product line.
16 bits
17 sixteen-bit words = 34 bytes = 272 bits
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16 bits
50 frames/sec = 192 bits/frame). Otherwise, when the data
16 bits
page 32
20 ms frame
16 bits
In most cases, when a controller is present
16 bits
(12) 16 bits words of data (192 bits)
16 bits
Voice Data Bits
16 bits
16 bits
In addition to these most
Every 20 milliseconds the
16 bits
16 bits
16 bits
16 bits
16 bits